12个I / O端口............................................ .................................................. .... 71

12.1概述..............................................................................................................71

12.2端口作为通用数字I / O .......................................... ........................................ 72

12.3端口的第二功能.............................................. ......................................... 76

12.4寄存器说明............................................... .............................................. 87

13 8位定时器/计数器与PWM ......................................... ................... 89

13.1特点...............................................................................................................89

13.2概述..............................................................................................................89

13.3定时器/计数器时钟源............................................ .................................. 91

13.4计数器单元.........................................................................................................91

13.5输出比较单元.............................................. ............................................. 92

13.6比较匹配输出单元............................................. .................................... 93

13.7工作模式.............................................. ................................................ 94

13.8定时器/计数器时序图............................................ .............................. 99

13.9寄存器说明............................................... ............................................ 101

14个16位定时器/计数器与PWM ......................................... ............... 108

14.1特点.............................................................................................................108

14.2概述............................................................................................................108

14.3访问16位寄存器............................................ ..................................... 110

14.4定时器/计数器时钟源............................................ ................................ 113

14.5计数器单元.......................................................................................................114

14.6输入捕捉单元.............................................. ................................................ 115

14.7输出比较单元.............................................. .......................................... 117

14.8比较匹配输出单元............................................. .................................. 119

14.9工作模式.............................................. .............................................. 120

14.10定时器/计数器时序图............................................ .......................... 127

14.11寄存器说明............................................... .......................................... 130

15定时器/计数器和定时器/计数器预分频器.............................. 137

15.1寄存器说明............................................... ............................................ 139

16 8位定时器/计数器，具有PWM和异步操作...... 140

16.1特点.............................................................................................................140

16.2概述............................................................................................................140

16.3定时器/计数器时钟源............................................ ................................ 141

16.4计数器单元.......................................................................................................141

16.5输出比较单元.............................................. ........................................... 142

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2545J–AVR–12/06